Medicine & USMLE

Class 1C Antiarrhythmics

Cardio Drugs - Antiarrhythmics
  1. Diltiazem and Verapamil (Calcium Channel Blockers)
  2. Class 1A Antiarrhythmics
  3. Class 1B Antiarrhythmics
  4. Class 1C Antiarrhythmics
  5. Class 3 Antiarrhythmics
  6. Amiodarone Side Effects
  7. Adenosine


Class 1C antiarrhythmics include the drugs propafenone and flecainide.

These drugs work as sodium channel blockers, slowing the conduction in the heart’s electrical system.

As antiarrhythmics, these medications can be used to treat SVT and v-tach.

Side effects may include new or worsening arrhythmias, dizziness, heart failure, and hypotension.

Key Points

  • Class 1C Antiarrhythmics
    • Drug Names
      • Propafenone (Rythmol)
      • Flecainide (Tambocor)
    • Mechanism
      • Sodium channel blocker
        • Slows conduction in the atria, ventricles, and His-Purkinje system
    • Clinical Use
      • Treats SVT
        • A fast heart rhythm that originates above the ventricles
        • Slowing down the electrical conduction in the atria helps treat SVT
      • Treats Ventricular Tachycardia
        • Used as a last resort after safer alternatives have been tried
        • Slowing down the electrical conduction in the ventricles helps treat v-tach
    • Side Effects
      • May worsen or cause new arrhythmias
        • Any drug that alters the heart’s electrical conduction has the potential to cause new arrhythmias
        • Carefully monitor heart rhythm during treatment
      • Heart failure
        • Use with caution in patients with existing heart failure or who are at risk of developing it
      • Dizziness (Orthostatic Hypotension)
        • Teach patients to change positions slowly to avoid dizziness and falls
      • Hypotension
        • Monitor blood pressure